Bluetooth: Support  HFP Client role on Bluedroid.

Implementation changes to support HFP Client role
on Bluedroid stack

Change-Id: Ie37e95d3b0e3f785af818fb495c835e420792f4d
(cherry picked from commit 072fad9a9a17c2a31660e7ac6cd6eba82d63fe50)
(cherry picked from commit 559508238c2fe1f8f10049549b8a29053399407c)